Clockwork movement for a projectile



Sept. 27, 1955 G. KUHN CLOCKWORK MOVEMENT FOR A PROJECTILE 4 Sheets-Sheet 1 Filed Oct. 3 1951 Z72v72Z 0/ 5 Georg s M572 Sept, 27, 1955 G. KUHN CLOCKWORK MOVEMENT FOR A PROJECTILE 4 Sheets-shew- 2 Filed Oct. 3', 1951 7? vewZm- 5 Gear-96a h ukn Sept. 27, 1955 G. KUHN 2,718,850

CLOCKWORK MOVEMENT FOR PROJECTILE Filed Oct. 5, 1951 4 Sheets-Sheet 3 Fig.5

Sept. 27, 1955 United States Patent '0 CLOCKWORK MOVEMENT FOR A PROJECTILE Georges Kuhn, Geneva, Switzerland, assignor to Mefina S. A., Binningen, Switzerland, a company of Switzerland Application October 3, 1951, Serial No. 249,479 Claims priority, application Switzerland April 13, 1951 3 Claims. (Cl. 102-83) Projectile fuses such as for example those adapted for explosive shells, must be more and more guaranteed against premature operation due to any cause whatsoever.

For this purpose means have already been provided for avoiding the transmission of a spontaneous explosion of the parts sensitive to the ignition to the main charge of a shell, this spontaneous explosion being capable of being produced for example by long storage or by shocks. These means, commonly called detonator safety devices, consist in separating the parts sensitive to firing, from the main charge which is less sensitive. The separated portions are placed into instantaneous communication after the firing of the shot or, at least later, after the cessation of acceleration. In other forms of construction, the placing in communication of the separated parts is retarded by pyrophoric means. However, these safety devices for the detonator can only be used in practice in connection with fuses of large calibre by reason of their size.

The present invention has for its subject a clockwork movement for a projectile, acting as a safety device for the detonator.

The clockwork movement has a movable member set in operation after the firing of the shot, and which controls the movement towards its armed position, of at least a portion of the primer of the projectile, mounted on a movable part, and holding it spaced from its armed position and from the main charge, in the unarmed position of the fuse and from the beginning of firing, during a period of time determined by the operation of the movement.

Two forms of construction of the subject of the invention, applied to gyratory shells, are shown by way of example in the accompanying drawings, wherein:

Fig. l is a view in axial section of a first form of construction of the safety device for the detonator combined with a clockwork movement, the members being shown in the unarmed position.

Fig. 2 is a section on the line II-II of Fig. l, and Fig. 3 is a section on the line III-III of Fig. 1.

Fig. 4 is a section similar to Fig. 2 showing the position of the members in the armed position.

Fig. 5 shows, in elevation and in section a second form of construction applied to a fuse of small calibre with an automatic destruction device.

Fig. 6 is a view in cross section on the line VIVI of Fig. 5 with the parts in unarmed position.

Fig. 7 is a cross section on the line VII-VII of Fig. 5 with the parts in armed position.

The movement shown in Figs. 1 to 4 is applied in a general manner to all projectiles of large or average calibre. As shown, the clockwork movement is formed by a balance wheel 30 pivoting on an arbor 30a the axis of which is concentric with that of the fuse. The balance wheel (Fig. 3) is provided with a pallet 30b in engagement with an escapement wheel 31 secured to apinion 32 which meshes with a gear wheel 33. The latter is secured to a pinion 34 meshing with the teeth 35 (Fig. 4) of a movable member formed by a mass 36 pivoted eccentrically at 36a relatively to the axis of the fuse. The mass 36 is held in the unarmed position of the fuse, in the position shown in Fig. 2, by a centrifugal bolt 37 subjected to the action of a spring 38. By the shape imparted thereto and by locating the lead body 36b, the position of the centre of gravity of the mass 36 is so selected that it is located in the part of said mass included in the semicircle having as base diameter the line connecting the axis of rotation of the projectile to the pivotal axis 36a of the mass 36, and which, relatively to this line, is located on the side towards which the movable member moves when leaving its unarmed position, so that the mass 36 cannot move angularly at least during the greater portion of the period of angular acceleration of the projectile. The movable safety member of the detonator is formed by a double armed lever 39 pivoted at its central portion on a pivot 40. Said lever has at the end of one of its arms a hole in which is mounted the sensitive part 7 of the primer. The distance between the pivot 40 and the axis of the fuse corresponds with that between the pivot 40 and the axis of the hole containing the sensitive part 7. The lever 39 is unbalanced, that is to say that its centre of gravity is located outside its pivotal axis, on the side opposite the sensitive part 7, so that it tends quite naturally, under the action of centrifugal force, to assume the position shown in Fig. 4, the sensitive part 7 being then in the armed position, that is to say it establishes communication between the primer and the main charge. The lever 39 is secured to a segment of a disc 41 having a notch 42, into which enters, in the position shown in Fig. 2; a circular shoulder of the mass 36, concentric to its axis of rotation 36a. 1

In the position shown in Fig. 2, the sensitive part 7 is located between the two plates of the movement and no communication is possible with the main charge of the projectile.

The circular shoulder of the mass 36 surrounding its axis of rotation has on the half thereof opposite the body of the mass 36 a cut-away portion 43 forming an escape for the segment 41, when the mass has moved, after the firing of the shot, up to the position shown in Fig. 4, in which it bears against a fixed stop 44.

A stop 45 is provided for the lever 39, when it is in its armed position (Fig. 4), in which it is locked by a centrifugal bolt 46.

In the construction shown, the unbalancing of the lever' 39 is produced by a mass 47, for example of lead, located in a recess of its arm, opposite to that carrying the sensitive part 7.

1 The operation of this form of construction is as folows:

At the commencement of firing all the parts are in the position shown in Fig. 2.

Under the action of centrifugal force, the bolt 37 bears against the wall of the casing 48, against the action of its spring 38 and from the end of the period of angular acceleration of the projectile, the movement of rotation of the mass 36 sets the escapment in operation through time after firing the shot, there is thus also obtained in addition to the safety of the detonator, a safety over a defined distance in front of the muzzle.

During this 7 section of the trajectory, the shell cannot therefore be fired by the fuse.

For fuses of small calibre, in which it is not possible to mount a movement such as is shown in Figs. 1 to 4, by reason of its size, a simplified form of construction is provided having the same guarantees as regards safety, but of very reduced size.

As shown in 'Fig. 5, the fuse F is provided with a striker 1 surrounded by a spring 1a, impact mechanism 1b and its support 10 the usual muzzle and transport safety devices and a self destruction device.

The safety device for "the muzzle and transport is formed 'by centrifugal bolts 20 retaining the striker 1 until the moment of firing the shot and then during the period of acceleration of the projectile in the muzzle.

The selfdestruction device is provided with a member 21 sliding in a support 22 and subjected to the action of the spring 1a, as also that of centrifugal masses 23. These masses slide in radial guides of the member 21 and co-operate under the action of centrifugal force with ramps of the support 22.

Between the striker 1 and the detonating charge 2 with itscap 3 is placed a clockwork movement comprising a mass 4 pivoting eccentrically at 5 relatively to the axis of the striker 1 and held in the unarmed position, shown in the drawing, by a spring 6. The mass 4 contains the sensitive part 7 of the primer. In the position shown in Fig. 6, it will be seen that the striker cannot reach the sensitive part 7 located in the mass 4. By the shape imparted thereto, the position of the centre of gravity of the mass 4 is selected in such a manner that it cannot move angularly during the period of angular acceleration of the projectile.

The sensitive part 7 should produce the explosion of the detonating charge 2 by means of its cap 3 under the action of the striker when it is in its armed position (Fig. 7). The sensitive part 7 is located at a distance from the axis 5 equal to the distance separating thisfrom the axis of the striker 1. The mass 4 has teeth '8 concentric'to its pivotal axis 5. The teeth engage'with a pinion 9-of which the spindle 10 also carries at its upper end an escapement wheel 11 which co-operates with a balancer 12 pivoting on a spindle co-axial with that of the striker 1.

During the firing of the shot, and after the end of the period of angular acceleration of the projectile, the mass 4 tends to move under the action of centrifugal force, against the action of the spring 6. The teeth 8 drive the pinion 9 which can only turn to the extent as is-permitted whilst the escapement wheel '11 'co-operates with the balance wheel 12, whereby a predetermined retardation is produced in its movement. Acentrifugal bolt '13 is provided for retaining the part 4 in its armed position, when it is reached.

Such a device thus permits of obtaining, like the device describedwith reference to Figs. 1 to 4, in addition to the safety of the detonator, a safety over a definite distance in front of the muzzle. On this section of the trajectory the shell cannot therefore be fired by the fuse.

It will be understood that instead of one spring 6, a number thereof may be provided and that between the toothed sector 4 and the escapement 11 may be provided a number of wheels for obtaining a greater multiplication.

It is to be observed that, in the case of the second form of construction, the centrifugal locking member 13 may be omitted. Thus, at the end of the trajectory, if no impact is produced and the self-destruction device does not operate, the fuse is again rendered unarmed by the return rearwardly of the movable member 4, which return is produced by the spring 6.

The subject of the invention may naturally be applied to types of fuses other than that shown in the drawing, but it lends itself particularly to applications to fuses of small calibre, by reason of its small size.

From the foregoing description it will be seen that in the two forms of construction 'the striker cannot reach the detonating primer immediately on firing, but only after a predetermined period of time which depends on the adjustment of the clockwork movement. On the other hand, ignition of the sensitive part 7 produced accidentally either at rest or during the period of operation of the clockwork movement, cannot therefore produce the explosion of the detonating charge.

On the other hand in the two forms of construction described, the clockwork movement is reversible.

I claim:

1. A delayed arming ,fuse for a projectile comprising a movable member in the form of a mass pivotally mounted for movement under the action of centrifugal force about an axis eccentric with respect to the axis of the fuse, said member having a toothed rack segment thereon, a pinion meshing with said rack teeth, a clockwork escapement connected with said pinion for retarding the movement of said pinion and said member, the center of gravity of the movable member being located in the part of said member comprised in a semi-circle having as base diameter a line which connects the axis of rotation of the projectile to the pivotal axis of said movable member and which, relatively to said line, is located on the side to which the movable member moves from its unarmed position, and relative to said pivotal axis of the movable member is located on the side thereof so as to tend to move the movable member to its unarmed position during the period of angular acceleration of the projectile, a primer, means associated with said movable member for carrying the primer for movement from unarmed position to armed position under control of said movable member, so that movement of said primer towards its armed position cannot be effected until after the projectile has left the gun.

2. A delayed arming fuse for a projectile comprising a movable member in the form of a mass pivotally mounted for movement under the action of centrifugal force about an axis eccentric with respect to the axis of the fuse, said member having a toothed rack segment thereon, a pinion meshing with'said rack teeth, a clockwork escapement connected with said pinion for retarding the movement of said pinion and said member, the center of-gravity of the movable member being located in the part'of said member comprised in a semi-circle having as base diameter a line which connects the axis of rot-ation'of the projectileto the pivotal axis of said movable member and which, relatively to said line, is located on the side to which the movable member moves from its unarmedposition, and relative to-said pivotal axis of the movable member is located on the side thereof so as to tend tomove the movable-member to its unarmed position during-the periodof angular acceleration of the projectile, a primer, means associated with said movable member for carrying the primer for movement from unarmed position under control of said movable member, so that movement of said primer cannot be effected'until after the projectile has left the gun, and a spring urging said movable member to its-unarmedposition.

3. A delayed arming fuse for a projectile comprising a movable member in the form of a mass pivotally mounted for movement under the actionof centrifugal force about an axis eccentric with respect to-the axis of the fuse, said member having a toothed rack segment thereon, a pinion meshing with said rack teeth, a clockwork escapement connected with said pinion for retarding the movement of said pinion and said member, a primer movable from anunarmed position to an armed position, a'disc' carrying said primer eccentrically thereof, and mounted for pivotal movement about an axis parallel to the axis oftheprojectile, a hub'carried by the movable member'engagingthe periphery of the disc for preventing rotation of the disc, said hub having a notch in a portion thereof operable in the :armed position of the movable memberfor freeing :the disc,z.the center of gravity ofvthe Q movable member being located in the part of said member comprised in a semi-circle having as base diameter a line which connects the axiis of rotaton of the projectile to the pivotal axis of said movable member and which, relatively to said line, is located on the side to which the movable member moves from its unarmed position in such a manner that it cannot move angularly during the period of angular acceleration of the projectile, the movement of said primer being controlled by said movable weight References Cited in the file of this patent member, so that movement of said primer cannot be 10 2541082 effected until after the projectile has left the gun.

UNITED STATES PATENTS Brayton Nov. 17, 1925 McCaslin Aug. 10, 1948 McCaslin et a1 Aug. 31, 1948 McCaslin et al Dec. 28, 1948 McCaslin et a1 Aug. 23, 1949 Pink Nov. 21, 1950 McCaslin Feb. 13, 1951 FOREIGN PATENTS Great Britain Nov. 17, 1931 

